Electronic systems often utilize discrete electrical components that must be connected together using structures and devices that establish electrical and mechanical contact. Electrical signals enter, traverse and exit these electromechanical connection structures, which often represent the site of significant signal degradation due to attenuation, reflection, interference or skew, any of which contribute to signal degradation that may harm the performance of the system. System architects can maintain signal integrity by utilizing connection devices that wherever possible lower inductance, reduce parasitic capacitance, minimize signal distortion and reflections, eliminate skew, and match impedance. In addition, system architects can improve signal integrity by utilizing electrical connection structures that optimize electromechanical contact force and contact wipe.
Vias, or plated through holes, in printed circuit boards are structures commonly used to establish electromechanical connections between electrical components and printed circuit boards. Vias can cause significant harm to signal integrity. FIG. 1 illustrates a prior-art electrical connector system in which the electrical connector 101 attaches to a printed circuit board 102, where the printed circuit board contains multiple layers 103. A conductive pin 104 is inserted into a plated through hole 105 (which consists of a hole 106, drilled through the printed circuit board, and an annular pad 107—both of which are plated with a conductive material). In this illustration, the plated through holes create anchor points for the electrical connector, and the plated through hole makes an electrical connection between the conductive pin 104 and a trace 108 that may be located on the surface of the printed circuit board one or more layers within the printed circuit board. Many of the structures associated with vias incorporate capacitive stubs 105, 106, 107, which degrade signal integrity.
FIG. 2 illustrates prior art showing a typical electromechanical contact assembly comprising a post 201 inserted into a tuning fork receptacle 202. The structure of this assembly may have unwanted parasitic capacitances resulting from three elements: (1) the capacitive stub formed by the portion of post 203 that extends into the assembly beyond the electrical contact points 204; (2) the capacitive stubs formed by the two projections 205 that extend away from the assembly beyond the contact points 204; and (3) the 90 degree folds 206 in the tuning fork receptacle 202.
FIG. 2A illustrates a prior art electrical connection device wherein the electrical conductor 207, makes contact with an electrical contact pad 208 at the electrical contact point 210, which moves along the electrical contact pad 208 as force is applied to the electrical conductor 207, causing a wiping motion 211 known as “contact wipe”, which clears corrosion from the electrical contact pad 208 and improves the electrical connection at the electrical contact point 210. After the contact wiping motion is complete and the electrical interconnection has been established, the electrical contact pad 208 has a capacitive stub 209 to the right of the electrical interconnection point 210. The stub causes parasitic capacitance.
FIG. 3A illustrates an isometric view and an oblique side view of a common prior art electromechanical contact assembly comprising two electrical conductors 305, 306 to be brought together and mated, electrical conductor 305 having a conductive protrusion 307 is aligned toward the counterpart conductor 306. Conductive protrusion 307 focuses the force pressing conductive elements 305 and 306 together, creating a more focused area of contact. The advantage of adding a protrusion is that reducing the area where the contact force is brought to bear increases the force per unit of area at the point of contact, better overcoming corrosion and small imperfections on the surfaces of the conductive elements, both of which can cause signal degradation and can generate heat. The conductive protrusion 307 also creates capacitive stubs 308, 309, at the end of conductive elements 305 and 306, which capacitive stubs create parasitic capacitance that contributes to signal degradation.
Despite these and other efforts in the art, further improvement in cost and performance is possible by introducing novel elements, simplifying design and lowering manufacturing cost.